Sinks (closed depressions) and sinkholes develop in areas underlain by limestone bedrock. The conduits that facilitate subsurface soil movement and surface sinkhole formation are erratic and often too random to be mapped by test boring programs alone. Geophysics provides a density of data unobtainable by other methods, and can be used to fill-in between existing borings or to screen larger areas to identify anomalous areas that warrant investigation by test borings or wells.

Delta Geophysics can help you model limestone bedrock using a combination of geophysical field collection and processing techniques tuned to your site-specific conditions. Resistivity, seismic, micro-gravity, GPR and induction techniques all have a place in characterizing karst features.

APPLICATION

Environmental investigations use geophysical maps and cross sections to identify bedrock pinnacles, faults, solution zones, soil depths and zones of eluviation in the subsurface. These features control irregular contaminant pathways and areas of discrete groundwater flow that are extremely important to site characterization. Locating these features early in a project provides focus for more expensive follow-up drilling investigations.

Contractors use geophysics to obtain accurate estimates of rock excavation for bidding purposes, and authorities and municipalities use geophysics to provide accurate rock excavation quantities for bid specifications to avoid contract “extras” and cost overruns.

Sinkhole mitigation is guided by geophysical data that identifies the nature and extent of underground solution zones and soil movement within a sink-hole prone area. These areas can then be targeted by grouting programs to stabilize the subsurface.

BENEFIT

Delta Geophysics provides interpreted data that allows our clients to create a robust subsurface model early in a project. Let Delta apply their years of varied experience to provide you with the extra level of knowledge that will help make your geotechnical and environmental decisions today hold up tomorrow.

DELTA GEOPHYSICS USES THE FOLLOWING METHODS TO INVESTIGATE AND MAP KARST FEATURES: